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Author: Bekeschus, Sander × Subject: reactive oxygen and nitrogen species ×

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    Singlet-Oxygen-Induced Phospholipase A2 Inhibition: A Major Role for Interfacial Tryptophan Dioxidation
    (Weinheim : Wiley-VCH, 2021) Nasri, Zahra; Memari, Seyedali; Wenske, Sebastian; Clemen, Ramona; Martens, Ulrike; Delcea, Mihaela; Bekeschus, Sander; Weltmann, Klaus-Dieter; von Woedtke, Thomas; Wende, Kristian
    Several studies have revealed that various diseases such as cancer have been associated with elevated phospholipase A2 (PLA2) activity. Therefore, the regulation of PLA2 catalytic activity is undoubtedly vital. In this study, effective inactivation of PLA2 due to reactive species produced from cold physical plasma as a source to model oxidative stress is reported. We found singlet oxygen to be the most relevant active agent in PLA2 inhibition. A more detailed analysis of the plasma-treated PLA2 identified tryptophan 128 as a hot spot, rich in double oxidation. The significant dioxidation of this interfacial tryptophan resulted in an N-formylkynurenine product via the oxidative opening of the tryptophan indole ring. Molecular dynamics simulation indicated that the efficient interactions between the tryptophan residue and phospholipids are eliminated following tryptophan dioxidation. As interfacial tryptophan residues are predominantly involved in the attaching of membrane enzymes to the bilayers, tryptophan dioxidation and indole ring opening leads to the loss of essential interactions for enzyme binding and, consequently, enzyme inactivation. © 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH
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    Hyperspectral Imaging of Wounds Reveals Augmented Tissue Oxygenation following Cold Physical Plasma Treatment in Vivo
    (New York, NY : IEEE, 2021) Schmidt, Anke; Niesner, Felix; von Woedtke, Thomas; Bekeschus, Sander
    Efficient vascularization of skin tissue supports wound healing in response to injury. This includes elevated blood circulation, tissue oxygenation, and perfusion. Cold physical plasma promotes wound healing in animal models and humans. Physical plasmas are multicomponent systems that generate several physicochemical effectors, such as ions, electrons, reactive oxygen and nitrogen species, and UV radiation. However, the consequences of plasma treatment on wound oxygenation and perfusion, vital processes to promote tissue regeneration, are largely unexplored. We used a novel hyperspectral imaging (HSI) system and a murine dermal full-thickness wound model in combination with kINPen argon plasma jet treatment to address this question. Plasma treatment promoted tissue oxygenation in superficial as well as deep (6 mm) layers of wound tissue. In addition to perfusion changes, we found a wound healing stage-dependent shift of tissue hemoglobin and tissue water index during reactive species-driven wound healing. Contactless, fast monitoring of medical parameters in real-time using HSI revealed a plasma-supporting effect in wound healing together with precise information about biological surface-specific features.